Corrosion-inhibited quaternary ammonium compositions



2,786,797 coRRosIoN-mrnBrrED QUATERNARY AMMONIUM COMPOSITIONS Harold G. Lederer, Longport; N. J.,-assignor'to R. M.

Hollingshead Corporation, Camden, N. J., a corporation of New Jersey No Drawing. Application May 18, 1954, Serial No.430,720

9 Claims. or. 167 30) The present invention relates to a bactericidal composition and more particularly to a solution suitable for sterilizing medical instruments and the like characterized by goodbactericidal properties and a high degree of stability.

One of the principal ingredients of the composition of the present invention consists of a quaternary ammonium compound or a mixture of such compounds. For the past several years a large number of quaternary ammonium compounds have been investigated and tested with regard to bactericidal power. It has been found that there are a number of quaternary ammonium compounds having satisfactory bactericidal power but it has also been found that a problem exists in stabilizing solutions of such compounds while at the same time retaining the desired bactericidal properties. I have found that the use of propylene glycol and sodium nitrite in the manner hereinafter described provides, in conjunction with a quaternary ammonium compound and water, a highly satisfactory sterilizing solution which has sufficient bactericidal properties to carry out sterilization of medical instruments even where the solution is used cold while at the same time remaining stable 'and non-corrosive. This latter characteristic is of particular importance where metal instruments are to be sterilized.

Accordingly the principal object of the present invention is to provide a bactericidal solution containing a quaternary ammonium compound and having sterilizing characteristics while at the same time being stable and non-corrosive to metals under normal conditions of storage or use.

The ingredients making up a preferred example illustrating the present invention and the relative amounts thereof are set forth in the following example:

Example I Percentage by weight Methyl dodecyl benzyl ammonium chloride 17.5 Propylene glycol 20.0 Sodium nitrite 20.0 Water 42.5

The solution of the above example is made up by first mixing the sodium nitrite and the water and then adding the propylene glycol. The quaternary ammonium compound is then slowly added with continuous stirring. Best results are obtained by mixing in the temperature range of about 140 F. to 150 F. The quaternary ammonium compound should be added at a rate corresponding to about a total time of about 20 minutes for a 2,000 gallon batch. This is done with continuous stirring. At lower temperatures more time will be required and at room temperature continuous stirring for about 24 hours would be necessary. After the quaternary ammonium compound has been added, the mixture is filtered and the pH is then adjusted in the range between 7.5 and 10.5 by adding a small amount of technical grade sodium hydroxide. The amount required to bring the solution within the desired pH range is about .005% of the total rates Patent 2,786,797 Patented Mar. 26, 19.57

\ 2 weight of the solution following the addition of all of the quaternary ammonium compound.

While the invention has been described above by referenceto a particular quaternary ammonium compound, I have found that other quaternary ammonium compounds can be used. Included among thes'eare th'efollowing: l

Alkyldimethylbenzylammonium chloride Diisobutyl phenoxyethoxyethyldimethylbenzylammonium chloride Alkylarylpyridinium chloride 9-octadecenylethyldimethylammonium bromide Cetyldimethylbenzylammonium chloride Dodecyldimethylamine oxide 9-octadecenyldime thylamine oxide 7 Cetyldimethylamine Any of the above may be used in the practice of the present invention either alone or in admixture in the percentage by weight indicated in Example I. Since the relative amounts will be the same for all of the ingredients of Example I in all cases, it is felt that a repetition of Example I substituting each of the above listed quaternary ammonium compounds for the particular quaternary ammonium compound of Example I would unnecessarily extend the present specification and, therefore, the above list has been provided in lieu thereof. However, it is my intention that this should be taken as a disclosure of all of the examples which would result from such substitution.

The mechanism responsible for the usual corrosion and rusting difficulties encountered in the use of quaternary ammonium compound solutions in the presence of metals is not entirely understood. Likewise I am not certain as to the complete explanation of the surprising lack of corrosion resulting from the use of sodium nitrite and propylene glycol in the invention as described above. However, exhaustive tests of the various sterilizing solutions disclosed above have demonstrated beyond question that a significant anti-corrosion result is achieved.

Throughout this specification and claims, it is intended that equivalent materials shall be included as coming within the present invention.

Having thus described my invention, I claim:

1. An inhibited bactericidal aqueous solution for sterilizing metal objects comprising a bactericidal quaternary ammonium compound containing a stabilizer consisting essentially of propylene glycol and sodium nitrite, said solution containing hydroxyl ion in an amount to provide a pH in the range of about 7.5 to about 10.5.

2. The solution defined in claim 1 wherein the quaternary ammonium compound is alkyl benzyl ammonium chloride.

3. The solution defined in claim 1 wherein the quaternary ammonium compound is methyl dodecyl benzyl ammonium chloride.

4. A sterilizing solution for medical instruments and the like having a pH in the range of about 7.5 to 10.5 comprising the following ingredients in substantially the relative amounts stated:

Percentage by weight Bactericidal quaternary ammonium compound 17.5 Propylene glycol 20.0 Sodium nitrite 20.0 Water 42.5

5. A sterilizing solution for medical instruments and the like having a pH in the range of about 7.5 to 10.5 comprising the following ingredients in substantially the relative amounts stated:

Percentage by weight Methyl dodecyl benzyl ammonium chloride 17.5 Propylene glycol 20.0 Sodium nitrite 20.0 Water 42.5

6. An inhibited aqueous solution for contact with metal objects without corroding the same comprising a quaternary ammonium compound containing a stabilizer consisting essentially of propylene glycol and sodium nitrite, said solution containing hydroxyl ion in an amount to provide a pH in the range of about 7.5 to 10.5.

7. The inhibited aqueous solution defined in claim 6 wherein the quaternary ammonium compound is diisobutyl phenoxyethoxyethyldimethylbenzylammonium chloride.

8. The inhibited aqueous solution defined in claim 6 wherein the quaternary ammonium compound is alkarylpyridinium chloride.

9. The inhibited aqueous solution defined iin claim 6 wherein the quaternary ammonium compound is cetyltrimethylammonium bromide.

OTHER REFERENCES Drug and Cosmetic Ind., February 1947, vol. 60, No. 2, pp. -182 and 268-271.

Drug and Cosmetic 1nd, May 1949, vol. 64, No. 5, pages 631-636 (634, 635 pertinent). 

1. AN INHIBITED BACTERICIDAL AQUEOUS SOLUTION FOR STERILIZING METAL OBJECTS COMPRISING A BACTERICIDAL QUATERNARY AMMONIUM COMPOUND CONTAINING A STABILIZER CONSISTING ESSENTIALLY OF PROPYLENE GLYCOL AND SODIUM NITRITE, SAID SOLUTION CONTAININIG HYDROXYL ION IN AN AMOUNT TO PROVIDE A PH IN THE RANGE OF ABOUT 7.5 ABOUT 10.5. 